I've not been exceptionally impressed with the build quality of Borla headers I've seen in the past. The header tubes seem a bit thin, and I'm leery of their welds. However, it's been a while, so maybe they've improved since I last experienced one...?
Personally, I have a Thorley header and I love it. The part number is 634Y for F.I. heads. If your 4.0 head is off a fuelie Jeep, it should bolt right on.
Both the Thorley and the Borla have CARB EO numbers, and thus both have the O2 bung.
[b]'94 YJ Sahara Hardtop[/b]
4.0L / AX-15 / Stock NP231 / Stock D30 (open) / D60 (35-spline, Detroit locker, Moser axles) / rear disc brakes / 4.56 gears / Advanced Adapters SYE & CV Shaft / 33" BFG MT-KM's / Thorley Header / Magnaflow Muffler / BesTop Flares